1. Field of the Invention
The present invention relates to a three-dimensional object forming apparatus and, more particularly to a three-dimensional object forming apparatus and a method for forming a three-dimensional object.
2. Description of Related Art
Rapid prototyping (RP) is developed according to the concept of a laminating process for forming pyramids. The technical feature of the rapid prototyping is rapid shaping, and transforming designed programs with complex configurations into three-dimensional (3D) models automatically and rapidly without using any cutting tools, molds and fixtures. Hence, the rapid prototyping can greatly reduce the study times and the research costs of new products, and ensure the time-to-market and the first-time success rate of the new products. The rapid prototyping is a more complete and conventional tool of product design for technical personnel to introduce new products to other technical personnel and non-technical personnel such as an enterprise's decision makers and users. Therefore, it is possible to increase the competitiveness of the products on the market and the rapid response of enterprises to the market.
Currently, the rapid prototyping technique generates 3D models by combining printing techniques and precise positioning carrier techniques. The process comprises the following steps: spreading a layer of powder on a carrier, printing an adhesive with high viscosity on parts of the powder through an ink-jet printing process to make the adhesive and the powder stick together and solidify, and repeating the aforementioned steps to laminate layer by layer to obtain a 3D model.
However, the printing heads of the printing apparatus generally used in the rapid prototyping technique are not sealed, when the ink-jet printing process is not being carried out. Hence, the remaining adhesive may dry on the printing heads or in the storage tank. The dried adhesive residue may impair the subsequent operation of the printing apparatus, and hence the benefits of the system cannot be ensured.
The rapid prototyping technique is known as the fastest molding technique currently available. However, no matter what the mold's size is or how the apparatus is modified, several, even tens of hours are spent to obtain a 3D model. In addition, when the printing head is blocked and the blocked printing head is not found or determined timely during the process of lamination, significant amounts of time and materials are wasted.
Additionally, the printing rate of spraying the printing adhesive with high viscosity is 8 m/sec, during the process of spraying the printing adhesive to form the model. At the instant that the droplets of the printing adhesive adhere to the powder, the nano-sized powder grains not adhered to the droplets may float in the air due to turbulence arising from the high printing rate. Furthermore, during the process of powder supply and object formation, the powder may also circulate in the air when the lamination of the powder is delivered. Besides, the conventional apparatus does not comprise a quantitative powder supplying device, so the remaining powder have to be delivered back into the recycle tank. During delivering of the remaining powder, the powder may descend inappropriately, causing pollution as well as waste of energy. Furthermore, excessive time is spent after each powder spreading step and several hours have to be spent waiting for the completed model to dry. If the strength of the model is insufficient or the model is not taken out properly, damage may occur thereto. Hence, the durations of both the fabrication and drying processes are not satisfactory for the industry. Also, the single direction processes of powder spreading and printing can only be used herein, because the precision of the printing position cannot be achieved; therefore, the time of shaping is also increased due to the single direction processes.
In addition, when the apparatus is in a standby mode for a long time or the printing head is idle, the printing adhesive residue clogs the wipers and sealing units in the maintenance device, which is particularly aggravated by hardening of the adhesive. Also, the circulating powder generated in the processes of powder spreading or printing impair the functions of devices and components.
According to the conventional printing module using a single-direction powder spreading process and a single-direction printing process, the printing module supplies powder from the start side to the finish side, spreads those powder from the end side to the start side, and then prints from start side to the finish side. Therefore, the preparing time is too long, and the time for manufacturing models cannot be fully utilized.
Therefore, it is desirable to provide a three-dimensional object forming apparatus and a method for forming a three-dimensional object to obviate the aforementioned problems in the art.